1st timer on uneven concrete floor

[Jock McG]

Hi all. Good forum - been reading it for years.
Now got to 1st major flooring job (9mm floor tiles) on new conservatory concrete floor base of 17m2 and need some advice - trying not to use a leveling screed and build up with adhesive - what do you think?
Sadly when floor was screeded we had a prob and as aresult have a high spot and depression (not just the floor either...).
On the diagram the RED area is the back/house wall and the slurry did not level down during screed (under an overhang) and has give us a high spot area along it's length)
The GREEN area is a depression caused when trying to polish when still wet.
The follr drops from the RED area to the outermost projection at top of GREEN are and at it's lowest point is 10-15mm below rest of area.
Most of surrounding area is 20mm below our finished surface height (we cannot change that) so minus the 9mm for tiles leaves us a good 11mm for adhesive. Problem occours when we get to the depression which then means upto 26mm adhesive to get to level - that area is about 4m2.
Do you suggest anything other than building up with adhesive as I want to avoid if poss using a leveling compound?

 

[WetSaw]

Why do you want to avoid SLC? You'll find it much easier than trying to build up with adhesive and you don't have to worry about exceeding the depth limits of adhesive.

 

[Flintstone]

I would not attempt to sort Those issues out simply by building up adhesive. You will find it very hard to get a nice flat finish and have adequate coverage between the tile and the floor. Use levelling compound, it's made for this exact situation

 

[Flintstone]

If your concerned about your ability to use it, don't be!

 

[Jock McG]

Have used it bofore on smaller areas - biggest concern, other than the size of the space, is overfilling it! The complete base with floor and brickwork are at the same level. The aluminium conservatory is stood on top of that so what you have is essentially a 20mm deep swing pool type space internally. Now that is the absolute max we can build upto including the 9mm tiles! All 3 doors open inwards and if it is overfilled with the slurry then we are b*gger*d as there will be no room for tiles/adhesive. Even more complicated by the fact that the high spot is the red zone for the house wall and the low spot is the furthest away so by the time you have poured the slurry to suit the red high spot it could be too little or too much! The margin for error is zero.
Does that make sense?

 

[WetSaw]

According to your drawing you have a "pool" . Just level that area if you are worried about the overall level getting too high. You may just have to accept that the floor is flat not level if there's no height to play with by the house.

 

[LM]

Couldn't you take the red area down with a grinding cup then fill up the green area to meet the new reduced height?

 

[Flintstone]

You don't really need to be level, just flat

 

[Jock McG]

The Red area will need to be ground 5.5mts x 4-500mm wide and come down is spots about 10mm but sems as thoug it's goint to be the only way - helluva mess inside a new glass build though!
Decided in meantime to put some levelling compound on the majority area - got Mapei for the job.
Any suggestions for a good runny mix from the experts? Mapei say use only 4.5lts/25kgs - sounds very dry mix and this being winter temps inside theis 17m2 x 2mt high floor to glass unit are understandably chilly when the sun drops.

 

[WetSaw]

Mix to the manufacturers specification, do not add more than the maximum amount of water specified. You'll be surprised how runny it is!

 

[LM]

The Red area will need to be ground 5.5mts x 4-500mm wide and come down is spots about 10mm but sems as thoug it's goint to be the only way - helluva mess inside a new glass build though!
Decided in meantime to put some levelling compound on the majority area - got Mapei for the job.
Any suggestions for a good runny mix from the experts? Mapei say use only 4.5lts/25kgs - sounds very dry mix and this being winter temps inside theis 17m2 x 2mt high floor to glass unit are understandably chilly when the sun drops.

Hire a dustless system for the job, it'll be worth it or buy a shrowed attachment for a vacuum.

 

[Jock McG]

All good sound advise - cheers.
Final (hopefully!) question - as per attached picture I will be using 300mm x 10mm mosaic tiles for edging and as you can see the cut angle is going to be 11.25 deg (I have to cut 18 of them) - anyone got tips on best way to cut with a wet table top saw?

 

[LM]

All good sound advise - cheers.
Final (hopefully!) question - as per attached picture I will be using 300mm x 10mm mosaic tiles for edging and as you can see the cut angle is going to be 11.25 deg (I have to cut 18 of them) - anyone got tips on best way to cut with a wet table top saw?

Fashion a guide from plywood or cementboard at the required angle to rest your tile on and position it on the main bar and simply push through the cutting wheel or pull the blade over which ever the case.

 

[stuey72]

Similar job few months the back.

Tented entire area off, and ground down high spots with diamond cup wheel on a 4-1/2 grinder. Prepare for zero visibility and a shitstorm of dust on epic Sahara desert proportions. Looked like an earthquake survivor after 3 hours of grinding and a burnt out Makita grinder as a souvenir.

Hire a professional grinder and extract system.

 

[Jock McG]

Update: Used the Mapei self levelling and got 10m2 for 3 bags - did'nt realise floor was so far out!
Now setting tiles in - started with Topps Tiles slow set adhesive - anyone used it before?
Mix says 4kgs to 1 lit water - that mix is like treacle! Torturous to mix and even with the floor level brought up we got only 8 tiles for 12kgs adhesive (not inc water) and thats using a 20x10 round notch trowel and back buttering tiles to get to level. Anyone used it before with a thinner dilution? It's like pushing cold toffee around!